Tippman C Ignition - possible for spudguns?

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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Hotwired
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Thu Apr 02, 2009 1:41 pm

Ah yes and so do I. I also have one which creates about 20 sparks per pull of the lever.

However you don't really want to be heaving away at the piezo when instead you can press a switch with no more resistance than bending a strip of milk bottle plastic... Plus of course I can make it such that it has lots of pretty LEDs which come on at important moments and make it look kewl.

Yes it all works when you get right down to it.

Just depends on how flash you want to be about it :)
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Sun Apr 12, 2009 6:27 pm

ramses wrote:...
nope, diode lasers (in laser pointers) work on around 3vdc. anything more than maybe 7V will fry them
THUNDERLORD wrote: Seen it work on balloons is all. (Black balloon inside, clear one outside)...
...nope, that was actually just melting a hole in the black balloon. also note that those were high power lasers (~200mw at least) whereas laser pointers are only maybe 5mw. these lasers are either modified from cheap ones(and don't last), made from DVD burners, or bought for obscenely large amounts of money.
Thanks for the info.
The only (old) book I saw years ago with a laser diagram showed a tube full of gas (different type for different colors) had a 100% reflective mirror on one side, and IIRC 95% reflective mirror on the front end.
High voltage ran through the gas (somehow) causing the gas to give off light, reflecting back and forth off the mirrors until the direction was straightened out the 95% reflective end.

Seems like a poor man's version like that could be designed.

I got to thinking of a combustion with a thick, clear polycarbonate breech.
the chamber could have a few (or more) angled mirror plates inside.
And when the laser ignition shines through, reflecting at the speed of light, the entire mixture would ignite rapidly.
Course some very clean burning mix would be needed or the mirrors and clear surfaces would dim from residue...

BTW, that's sort of off topic, but I was thinking of more compact ignition possibilities and got very side tracked.
Looks like a good part on the Tippman. 8)
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Sun Apr 12, 2009 7:13 pm

THUNDERLORD wrote: Thanks for the info.
I got to thinking of a combustion with a thick, clear polycarbonate breech.
the chamber could have a few (or more) angled mirror plates inside.
And when the laser ignition shines through, reflecting at the speed of light, the entire mixture would ignite rapidly.
Course some very clean burning mix would be needed or the mirrors and clear surfaces would dim from residue...
Won't work. You would need a massively powerful laser to get it to work since the gases in the chamber would absorb only a very tiny amount of the laser energy. In a colorless gas the beam is invisible and transfers very little energy to the gas.

Course, you could focus the laser on a match head, piece of paper, ....

I wonder if you could ifnite a clear chambered combustion using a magnifying glass to concentrate sunlight onto a match (stick, paper....) inside the chamber?

Indeed, I wonder if the blue laser from a DVD drive can ignite a match head? (Somebody must have tried that)
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Sun Apr 12, 2009 7:54 pm

jimmy101 wrote:Hotwired, what kind of transformers are you trying?

The tiny little "10KV" trigger transformers used in photoflashes? They can be had for cheap from many surplus places. Or, have you found something else?

TV flyback's will work of course but they are huge (relatively speaking), pricey and really not designed for this use.

Car ignition coils will also work but they are even bigger than flybacks.
The primary winding on the flash trigger transformers is high voltage. They are typically tripped with a 0.01 uF capacitor that is charged from the main 300 volt flash voltage. It would take quite a circuit to feed it from a AA battery.

Has anyone considered building an igniter circuit? They were used on antique coffee grinder gasoline engines before spark plugs took over. It is basically a set of points in the cylinder that is mechanically driven open and closed. A battery and an inductor (sometimes hand wound) completes the circuit. The battery provides current while the points are closed and the voltage spike as the points open creates a spark.

I learned this messing with antique gas engines. Near here they have a steam up for antique tractors every year.

http://www.antiquepowerland.com/
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Sun Apr 12, 2009 10:57 pm

Technician1002 wrote:The primary winding on the flash trigger transformers is high voltage. They are typically tripped with a 0.01 uF capacitor that is charged from the main 300 volt flash voltage. It would take quite a circuit to feed it from a AA battery.
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Next to the 1 penny coin which for reference is ~2cm diameter.

It's part of the ignition circuit I'm working on ^^

Looks like it'll end up about the same size as the Tippmann one but less sophisticated and producing a larger spark/arc.
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Mon Apr 13, 2009 5:50 am

One of the things I had thought about witht he Tippman was using it in rapid-fire set ups, as it would seem not to need any "charging" time between sparks. I'm guessing your set up HW will do the same thing?
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Mon Apr 13, 2009 7:10 am

:lol:

Maybe, maybe. Mine won't be controlled by a microchip that's for sure.

To be honest I couldn't say how that circuit operates, however I do know that what it is doing is discharging a capacitor through that coil. That is perfectly possible on a simple level.

Depends a lot on what you want out.

A small capacitor will charge fast but give a low current spark.

A large capacitor will charge relatively slowly but it will make a hell of a spark.

The Tippmann is certainly using a small capacitor, it's probably that blue/turquoise rectangle on the right. Obviously not electrolytic so it's going to have a small value at that size. Maybe a few nF at a few hundred volts.

The problem is that using that kind of value capacitor with what I have (as opposed to the custom circuit and coil Tippmann uses) doesn't actually produce a spark. Or if there is one it's invisible to eye. I've only got a spark capable of igniting a gas cloud by using a minimum of a 4.7uf capacitor (the largest "small" capacitor I have at the moment) that'll charge and fire fairly quickly, it'll never do auto but it will do semi.

Of course one thing you can do which the Tippman modules switching would probably die doing is also use a "large" capacitor - large being a flash camera sized one of 80-120uf. That makes the kind of spark which is more like a small flare because there's so much current.

But a large cap is not efficient for ignition, goes through AAA batteries fairly rapidly.

So all depends what you're after.
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Mon Apr 13, 2009 7:56 am

The other alternative could be something like the modern electronic iginition systems you get in things like chainsaws and leaf-blowers. They're more than capable of firing thousands of times a second.
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Hotwired
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Mon Apr 13, 2009 10:58 am

Absolutely.

Now compete with a price of £7, weight of ~100g and fit it into a pistol grip :wink:
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Mon Apr 13, 2009 11:21 am

Simple, i send you £7, you make it and send it to me and the Euro is so strong that I feel like I got a real bargain ;)

No seriously, huge kudos for doing it yourself, everytime I pick up a soldering iron I burn something, usually me.
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Mon Apr 13, 2009 3:16 pm

Hotwired wrote: A small capacitor will charge fast but give a low current spark.

A large capacitor will charge relatively slowly but it will make a hell of a spark.

The Tippmann is certainly using a small capacitor, it's probably that blue/turquoise rectangle on the right. Obviously not electrolytic so it's going to have a small value at that size. Maybe a few nF at a few hundred volts.

The problem is that using that kind of value capacitor with what I have (as opposed to the custom circuit and coil Tippmann uses) doesn't actually produce a spark. Or if there is one it's invisible to eye. I've only got a spark capable of igniting a gas cloud by using a minimum of a 4.7uf capacitor (the largest "small" capacitor I have at the moment) that'll charge and fire fairly quickly, it'll never do auto but it will do semi.
The caps used for this type of application are special low ESR ones (ESR=equivalent series resistance). For best results the ESR of the cap needs to be significantly lower than the resistance of the primary winding of the coil. Since the coils primary is probably just a couple turns of fine wire it's resistance is pretty small.

You can get low ESR caps from a place like Digikey or Mouser. The cap's are pretty cheap but the shipping will end up being more than the cost of the caps. The hard part is actually finding the type you need (capacitance and voltage rating in particular). A non-low ESR cap can be used but it won't work nearly as well. Most cheapo photoflash boards use an 0.022uF low ESR cap. One possibility is to wire a couple 0.022uF low esr caps scavenged from flash boards in parallel. The total capacitance is the sum of the individual capacitances. The total energy is proportional to the total capacitance.

Technician1002 said: The primary winding on the flash trigger transformers is high voltage. They are typically tripped with a 0.01 uF capacitor that is charged from the main 300 volt flash voltage. It would take quite a circuit to feed it from a AA battery.
No, not really. Any old flash board from a disposable camera will do exactly that. So for $0 you can get the complete circuit, including a functioning AA battery. :)
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Tue Apr 14, 2009 7:03 am

Actually I think the trigger cap is 2pf, making a conga line of those will be a pain.

I'm using a mess of flash and standard electrolytic types which work well enough for demonstration.

Ideally I'd like a big fat yellow capacitor (technical term) as seen here ^^
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Tue Apr 14, 2009 7:25 am

I know it fits more into sparker refference guide but one day I've found a site selling spare parts for home appliances and there was a deviced which creates sparks for gas plates... it was for ~5$

yeah I know it's mains powered but still... maybe someone would find it useful....

EDIT
ohhh I couldn't find it but I've found another one -> http://allegro.pl/item606369314_iskrown ... rcook.html

ohh there are some quite cheap solenoid valves as well-> http://allegro.pl/item606192422_elektro ... oover.html

the site is more less like eBay but I am sure you can find this stuff on ebay or somewhere else
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Tue Apr 14, 2009 8:12 am

jimmy101 wrote:
Hotwired wrote: A small capacitor will charge fast but give a low current spark.

A large capacitor will charge relatively slowly but it will make a hell of a spark.

The Tippmann is certainly using a small capacitor, it's probably that blue/turquoise rectangle on the right. Obviously not electrolytic so it's going to have a small value at that size. Maybe a few nF at a few hundred volts.

The problem is that using that kind of value capacitor with what I have (as opposed to the custom circuit and coil Tippmann uses) doesn't actually produce a spark. Or if there is one it's invisible to eye. I've only got a spark capable of igniting a gas cloud by using a minimum of a 4.7uf capacitor (the largest "small" capacitor I have at the moment) that'll charge and fire fairly quickly, it'll never do auto but it will do semi.
The caps used for this type of application are special low ESR ones (ESR=equivalent series resistance). For best results the ESR of the cap needs to be significantly lower than the resistance of the primary winding of the coil. Since the coils primary is probably just a couple turns of fine wire it's resistance is pretty small.

You can get low ESR caps from a place like Digikey or Mouser. The cap's are pretty cheap but the shipping will end up being more than the cost of the caps. The hard part is actually finding the type you need (capacitance and voltage rating in particular). A non-low ESR cap can be used but it won't work nearly as well. Most cheapo photoflash boards use an 0.022uF low ESR cap. One possibility is to wire a couple 0.022uF low esr caps scavenged from flash boards in parallel. The total capacitance is the sum of the individual capacitances. The total energy is proportional to the total capacitance.

Technician1002 said: The primary winding on the flash trigger transformers is high voltage. They are typically tripped with a 0.01 uF capacitor that is charged from the main 300 volt flash voltage. It would take quite a circuit to feed it from a AA battery.
No, not really. Any old flash board from a disposable camera will do exactly that. So for $0 you can get the complete circuit, including a functioning AA battery. :)
There are 2 animals we are talking about. 1 is the main flash cap. If you short it, you get the big spark. The trigger coil circuit to light the lamp is a low current high voltage coil like and ignition coil and a relatively small cap to dump a 200-300 volt spike on the primary much like a capacitor discharge ignition system in a car. The high voltage spike ionizes the gas in the flashtube so the primary flash current can flow. The trigger circuit is able to cycle several times/second. The main cap takes several seconds to recharge as that is the power discharge.

My orignial reply was regarding the trigger transformers purchased surplus cheap. It is true the disposable cameras come with the whole ball of wax.

It may be possible to use the trigger circuit without the main flash tube present as a CDI unit capable of high rep rates as the trigger cap takes very little time to charge. Don't spend a lot of money for special low ESR caps. That is for electrolytic caps. All mylar and disk ceramic caps are low ESR for high frequency use.
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Tue Apr 14, 2009 9:57 am

The trigger cap through the small coil I'm using does not produce a spark capable of igniting a gas stream, it's barely visible.

Enough of them together will work.
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